Pressure-pulse therapy, also known as shock-wave therapy, has many uses It is used in lithotripsy as a non-invasive technique for pulverizing kidney stones and calculi in the bladder and urethra. It is also used for dissolving lipids in cells close to the skin and in the pelvic region. In particular, it has many uses in orthopedic medicine, for example, as a therapeutic means for any of the following:    i. osteoporosis and the inducement of bone growth;    ii. joining of bone fracture, especially, ununion fractures, i.e., fractures that have failed to unite and heal;    iii. disintegration of calculi and (or) calcification in fibers, joints, and tendinitis; and    iv. pain relief in the cases of calcific tendinitis of the shoulder joint, tennis elbow, golf elbow, and plantar fasciitis (with and, without heel spur).
U.S. Pat. No. 4,620,545 “Non-Invasive Destruction of Kidney Stones” to Shene et al, whose disclosure is incorporated herein by reference, describes a pressure-pulse therapy apparatus which includes an ellipsoidal reflector, having a first focal point within the reflector's dome and a second focal point outside the reflector's dome. A flexible diaphragm caps the reflector, and the region contained by the reflector and the diaphragm is filled with a liquid medium, for pulse propagation. A pressure-pulse source is located at the first focal point, within the medium. This configuration provides that a portion of a pulse originating from the source, at the first focal point, will impinge on the reflector, be reflected by it, and be brought into focus at the second focal point. The reflector is movable and can be positioned so that the second focal point coincides with a concretion within the body that is to be pulverized. Sonic aiming means are used to detect the concretion and to direct the positioning of the reflector.
In general, pressure-pulse therapy is accompanied by an imaging means, such as the sonic aiming means of U.S. Pat. No. 4,620,545. The region for treatment is generally small, between 0.3 and 1.5 cm, and it is desirous to image the location in order for the therapy to be applied effectively. X-ray imaging may be used; however, with x-rays, the patient and the physician are exposed to radiation doses with each treatment.
PCT patent publication PCT WO 93/14720, “Method and Apparatus Particularly Useful for Treating Osteoporosis,” to Spector, whose disclosure is incorporated herein by reference, offers an alternative to the need for an imaging means. It has a generally parabolic reflector, which has a single focal point within the reflector's dome. A flexible diaphragm caps the reflector and the region contained by the reflector and the diaphragm is filled with a liquid medium, as in the previous patent. A pressure-pulse source is located at the focal point, within the liquid. This configuration provides that a portion of a pulse originating from the source, at the focal point, will impinge on the reflector, and be reflected by it, collimated. In other words, the reflected pulse will be a non-focusing wave, so focusing means are not essential. Pressure pulse therapy can thus be image free.
However, with a collimated beam, some pressure pulse energy is lost, when compared with a beam that is focused at the region for treatment. It would be desirable to direct more of the pressure-pulse energy at the region for treatment, without being dependent on an imaging means.